Chief - this is an interesting article on how many plate appearances it takes for a particular stat to become significant. for example, swing percentage becomes more likely than not to be a significant measure of a player's propensity to swing at 50 PAs, while HR/ FB stablizes at 300 PAs and batting average takes longer than a season to stabilize. It's kind of a seminal analytical article and, for example, would be useful to anyone trying to figure out when Mike Morse's numbers indicate a problem with him or something likely to straighten out.

maybe there is a stat geek thread where this is more appropriate, but what tends to happen is every few months someone starts a "What's this mean" stat thread rather than keeping that stuff consolidated.